Conventionally, in the assembly line of a vehicle, when a work is assembled to the vehicle, which is difficult for an operator to transfer, set, or assemble (called “a large work” involving a front window or a rear window), a work conveying apparatus is used, which assists to support the work, reduces the load to support the work for the operator, and which assists to convey the work, reduces the load to operate the work. Thus, such the work conveying apparatus is known as a power assist apparatus.
As the work conveying apparatus, JP-A-11-245124 discloses the work lifting apparatus including a holder and a supporter, the holder holds the work, the supporter moves the holder vertically and supports to the holder with inclination. This work lifting apparatus detects the inclination of the holder operated by the operator and lifts the holder by the supporter on the detected direction and angle about the inclination of the work.
Typically, the apparatus transfers the work to an assembling object, and assembles to an assemble position of the assembling object. When assembling to the assemble position, pressing the work to the assemble position, the apparatus assembles the window to the assembling object without fault.
Especially, if the work is a window involving a front window or a rear window, the work is assembled to a window-frame as the assembling object with a peripheral edge thereof coated by an adhesive. In order to adhere the window to the frame and to obtain adhesion strength and sealing property between the window and the frame all over the adhered periphery, the adhesive coating the peripheral edge of the window should be equally squashed and spread, pressing the peripheral edge of the window equally to the frame.
As shown in FIG. 12, when a work conveying apparatus 101 assembles a window 105 to a frame 107 of a vehicle body 107a, holding the window 105 by pads 130 disposed at a hold member 120 of the work conveying apparatus 101, transferring the window 105 to the frame 107a, assembling the window 105 to the frame 107a, the window 105 is pressed to the frame 107a by a robot arm 110 via the hold member 120.
When the window 105 is assembled to the frame 107a, inserting an up-stopper 105a (a portion formed in a craw shape) disposed at the upper side of the window 105 to a hole formed in the frame 107a, the window 105 assembled to the vehicle 105 is prevent from falling therefrom. Here, some pads 130 transfering the pressure from the arm 110 to the window 105 are disposed near the up-stopper 105a to insert the up-stopper 105a to the hole of the frame 7a without fault.
As shown in FIGS. 12 and 13, an adhesive 106 for adhering the window 105 to the frame 107a coats the peripheral edge of the window 105. The pads 130 for equally squashing the adhesive 106 all over the periphery are disposed with equal dimensions from the peripheral edge of the window 105 (as shown in FIG. 13, the pads 130 are disposed with dimensions da from the upper-end of the window 105 to the upper pads 130 and with dimensions db from the lower-end of the window 105 to the lower pads 130, the dimensions da and db are substantially same). As a result, the peripheral edge of the window 105 is contacted to the frame 107a with equal pressure.
Thus, disposing the pads 130 with equal dimensions da and db shown in FIG. 14, when the hold member 120 is pressed with robot arm 110 to apply equal pressing force to the window from each of the pads 130, all over the peripheral edge of the window 105 is equally contacted to the frame 107a. 
However, because of the variation in the holding position of the window 105 with the hold member 120, or the variation in the position of the vehicle transferred in the line against the apparatus 101, the pressing forces applied to the pads 130, 130 against the window 105 are not equal, all over the adhesive 106 coating the peripheral edge of the window 105 may not be equally squashed.
In the line assembling the various types of vehicle, what is called “the composite line,” the windows 105 are different in size or form within the vehicle types. Thus, the common hold member for all vehicle types is desired, including the plural pads 130, 130 for holding the window 105, in the light of the capital cost, production efficiency of the product line, and so on. Without changing the arrangement of the pads 130, 130, the hold member 120 (one-type hold member) is desired to hold the windows 105 with different sizes and forms.
Thus, in order to use the common hold member about all types of the window 105, typically, the pads 130, 130 are arranged to hold the smallest-size window 105.
However, when the large-size window 105 is held by the hold member 120 mentioned above, the upper-end side pads 130 is disposed near the up-stopper 105a as shown in FIG. 15, so that the lower-end side dimension db becomes longer than the upper-end side dimension da.
When the window 105 is held with the hold member to make the dimension db longer than dimension da and is pressed to the window frame 107a, the hold member 120 is pressed with the robot arm 110 to apply the equal pressing forces to the window 105 from each of the pads 130 as shown in FIG. 16; however, the lower-end of the window 105 is contacted to the frame 107a with lighter force than the upper-end of the window 105.
Thus, the adhesive 106 coating the lower-end of the window 105 is squashed badly, and the adhesion strength or the sealing property between the window 105 and the frame 107a may not be obtained all over the adhered periphery.
The objective of the invention is to provide an unexpected work conveying apparatus and work assembling method, enabled to equally press the peripheral edge of the work to the assembling object, when there occurs a variation in the holding position of the work involving the window by the hold member of the apparatus or in the position of the assembling object involving the vehicle transferred to the line with respect to the apparatus, and when one-type hold member holds and assembles the various-sizes or -forms works to the assembling object.